The D.C. hospital said the congressman's readmission to the ICU was due to "new concerns for infection." He was listed in serious condition.

Scalise was shot in Alexandria, Virginia on June 14 during a GOP practice for the annual Congressional Baseball Game. He and four others were injured when James T. Hodgkinson, of Illinois, opened fire on the field.

The Louisiana Republican had been transferred out of the ICU on June 22, when he was listed in fair condition. MedStar Washington said an update on Scalise's condition would be provided Thursday.